The experts have written an open letter urging Facebook to pull the child-focused messenger app, saying that “younger children are simply not ready to have social media accounts,” reports the Guardian. The letter was spearheaded by the Campaign for Commercial-Free Childhood and signed by over 100 child health experts, doctors, and educators. In it, the signatories argue: “At a time when there is mounting concern about how social media use affects adolescents’ well-being, it is particularly irresponsible to encourage children as young as pre-schoolers to start using a Facebook product.” The Messenger Kids app was launched in December and aimed at children under 13. It offers a host of parental controls, and Facebook says the data collected from the app will not be used for advertising purposes. Facebook has not yet responded to the open letter.